Electroadhesive gripping

ABSTRACT

An electroadhesive gripping device or system includes a plurality of electroadhesive gripping surfaces, each having electrode(s) and each configured to be placed against respective surface regions of a foreign object, such that one or more electroadhesive forces can be provided between the electroadhesive gripping surfaces and the foreign object. Such electroadhesive forces operating to hold the foreign object against the electroadhesive gripping surfaces while the foreign object is held or moved by the electroadhesive gripping system. The electroadhesive gripping surfaces can be arranged onto a plurality of continuous fingers, and various gripping surfaces on each finger can be coupled together and manipulated with respect to each other by an actuating component, such as a cable actuator. A variable voltage can be delivered to the electrodes to control the amount of electroadhesive force generated, such that only a portion of a foreign object is held or moved.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/303,216, filed Feb. 10, 2010, and entitled “ElectroadhesiveGripping,” which is incorporated by reference herein in its entirety andfor all purposes.

TECHNICAL FIELD

The present invention relates generally to the handling of materials,and more particularly to the use of electroadhesive force in thehandling of materials.

BACKGROUND

The mass production of products has led to many innovations over theyears. Substantial developments have been made in the industrialhandling of various materials and items, particularly in the area ofrobotics. For example, various types of robotics and other automatedsystems are now used in order to “pick and place” items during manymanufacturing and other materials handling processes. Such robotics andother systems can include robot arms that, for example, grip, liftand/or place an item as part of a designated process. Of course, othermanipulations and materials handling techniques can also be accomplishedby way of such robotics or other automated systems. Despite manyadvances over the years in this field, there are limitations as to whatcan be handled in such a manner.

Conventional robotic grippers typically use either suction or acombination of large normal forces and fine control with mechanicalactuation in order to grip objects. Such techniques have severaldrawbacks. For example, the use of suction tends to require smooth,clean, dry and generally flat surfaces, which limits the types andconditions of objects that can be gripped. Suction also tends to requirea lot of power for the pumps and is prone to leaks at any location on avacuum or low pressure seal, with a resulting loss of suction beingpotentially catastrophic. The use of mechanical actuation often requireslarge normal or “crushing” forces against an object, and also tends tolimit the ability to robotically grip fragile or delicate objects.Producing large forces also increases the cost of mechanical actuation.Mechanical pumps and conventional mechanical actuation with largecrushing forces also often require substantial weight, which is a majordisadvantage for some applications, such as the end of a robot arm whereadded mass must be supported. Furthermore, even when used with sturdyobjects, robotic arms, mechanical claws and the like can still leavedamaging marks on the surface of the object itself.

Alternative techniques for handling items and materials also havedrawbacks. For example, chemical adhesives can leave residues and tendto attract dust and other debris that reduce effectiveness. Chemicaladhesives can also require a significant amount of added force to undoor overcome a grip or attachment to an object once such a chemicaladhesive grip or attachment is applied, since the gripping interactionand force is typically not reversible in such instances.

Although many systems and techniques for handling materials in anautomated fashion have generally worked well in the past, there isalways a desired to provide alternative and improved ways of handlingitems. In particular, what is desirable are new automated systems andtechniques that permit the picking and placing or other handling ofobjects that are large, irregular shaped, dusty and/or fragile, andpreferably with little to no use of suction, chemical adhesives orsignificant mechanical normal forces against the objects.

SUMMARY

It is an advantage of the present invention to provide improvedautomated materials handling systems and techniques that permit thehandling of a wide variety of objects without the use of suction,chemical adhesives or significant mechanical normal forces against theobjects. This can be accomplished through the use of electroadhesiveforces in an electroadhesive gripping system, such that the object isheld or moved by way of such electroadhesive forces.

The present invention provides electroadhesion technology that permitscontrollable adherence between two objects, such as a controlledelectroadhesive gripper and a foreign object to be handled.Electroadhesion uses electrostatic forces of attraction produced by anelectrostatic adhesion voltage, which is applied using electrodes in anelectroadhesive device. The electrostatic adhesion voltage produces anelectric field and electrostatic adherence forces. When theelectroadhesive device is positioned against or near a surface of anobject to be handled, the electrostatic adherence forces hold the objectto the electroadhesive device. This can be used to increase traction orshear (i.e., anti-slip) forces between the electroadhesive device andthe handled object. Electrical control of the electrostatic adhesionvoltage permits the adhesion to be controllably and readily turned onand off. Variances in the electrostatic adhesion voltages can be used tovary the electroadhesive force.

In various embodiments of the present invention, an electroadhesivegripper, gripping system or device can include a first electroadhesiveend effector or gripping surface having at least one electrode and asecond electroadhesive end effector or gripping surface having at leastone electrode, wherein the first and second electroadhesive grippingsurfaces combine to provide an overall electroadhesive force thatoperates to hold a foreign object against the electroadhesive grippingsurfaces while the foreign object is held or moved by theelectroadhesive gripping system. The electroadhesive end effectors orgripping surfaces can be configured to be placed against a first surfaceregion of a foreign object having a three-dimensional shape, and can beadapted to be moved independently with respect to each other. In someembodiments, one or more of the electroadhesive gripping surfaces caninclude a deformable surface portion adapted to conform to at least oneaspect particular to a corresponding surface region of the foreignobject. Such a deformable surface portion can be adapted to move closerto the surface region of the foreign object when voltage is applied tothe respective electroadhesive gripping surface. The foreign object canhave a round, cylindrical or irregular three-dimensional shape, and/orbe fragile in some embodiments.

In some embodiments, the electroadhesive gripping system can be locatedon a single end effector that is either fixed in geometry or that isflexible and can wrap around various foreign objects, such as likefingers on a hand. Such embodiments can result in gripping forces thatare parallel to the various surfaces of a foreign object to be handled.Multiple electroadhesive gripping surfaces can be located on a singleend effector. Alternatively, multiple electroadhesive end effectors canbe used, with each end effector having one or more gripping surfaces. Insome embodiments, an electroadhesive end effector can resemble a humanhand. Alternatively, a single electroadhesive end effector can define athin and flexible veil having a plurality of electrode pairs in otherembodiments, with each electrode pair defining a separate grippingsurface.

An electroadhesive gripping surface can include a first electrodeconfigured to apply a first voltage at a first surface location at asurface region and a second electrode configured to apply a secondvoltage at a second surface location at the surface region of theforeign object, such that the difference in voltage between the firstvoltage and second voltage includes an electrostatic adhesion voltagethat produces a local electroadhesive force. In addition, an insulationmaterial can be disposed between the first and second electrodes, andcan be configured to substantially maintain the electrostatic adhesionvoltage difference between said first and second electrodes. In variousembodiments, the electroadhesive gripping surface can be less than about1 millimeter from the surface of the foreign object when anelectrostatic adhesion voltage is applied and/or maintained (i.e., ison).

A third electroadhesive gripping surface having at least one electrodecan similarly configured to be placed against a third surface region ofthe foreign object such that additional electroadhesive force can beapplied from the system to the foreign object. Further electroadhesivegripping surfaces may also be included in a similar manner Such variouselectroadhesive gripping surfaces can be or be part of anelectroadhesive gripping unit or gripping component.

In various detailed embodiments, an actuating component can be coupledto the first and second electroadhesive gripping surfaces, with such anactuating component being configured to help position each of saidelectroadhesive gripping surfaces with respect to the foreign object.Such an actuating component or system can also be used to shape one ormore electroadhesive end effectors and/or gripping surfaces so as toconform around an object. Such shaping can be similar to hands andfingers conforming to a foreign object to be gripped. Such an actuatingcomponent or system can be a cable driven by an actuator, anelectromagnetic motor, a stepper motor, a hydraulic system, a pneumaticsystem, a shape memory alloy, and an electroactive polymer, among otherpossible actuating components. In some embodiments, such as when theelectroadhesive surface can be a light thin film or veil, theelectroadhesion itself can provide actuation to grasp a foreign object.

In various embodiments, the overall electroadhesive force can be avariable force that depends upon a variable voltage delivered to theelectrodes of the electroadhesive gripping surfaces or end effectors.Such a variable overall electroadhesive force can be varied such thatonly a portion of the foreign object is held or moved, rather than theentire foreign object. A variable electroadhesive force can also be usedto modulate friction on the gripping surface, so as to repositionobjects by controllably sliding objects within or about the grippingsurface. The first and second electroadhesive gripping surfaces canoperate to pick, lift and place the foreign object in some embodiments,while in other embodiments the foreign object is only moved or held bythe gripping surfaces. In various embodiments, various substantialforces exerted against the foreign object by the electroadhesivegripping system while the foreign object is lifted or moved thereby areelectroadhesive forces.

In various embodiments, the first electroadhesive gripping surface canbe configured to move relative to both the foreign object and the secondelectroadhesive gripping surface while the electroadhesive grippingsystem is preparing to grip the foreign object. In some embodiments, thesecond electroadhesive gripping surface can similarly be configured tomove relative to both the foreign object and the first electroadhesivegripping surface while the electroadhesive gripping system is preparingto grip the foreign object. In some embodiments, the firstelectroadhesive gripping surface cannot move relative to the secondelectroadhesive gripping surface while the electroadhesive grippingsystem grips the foreign object. In some embodiments, the movement ofelectroadhesive gripping surfaces can supplement or replace the variousactuation methods or techniques provided herein.

In various embodiments, the electroadhesive gripping surfaces orgripping units can be formed along one or more continuous fingers of theelectroadhesive gripper, gripping system or device. Such continuousfingers can be adapted to extend around surfaces of the foreign objectin different directions. In particular, a first finger having a firstplurality of electroadhesive gripping surfaces, each including at leastone electrode, can be configured to be placed against a foreign objectsuch that an electroadhesive force between the electroadhesive grippingsurfaces and the foreign object can be generated. Also, a second fingerhaving a second plurality of electroadhesive gripping surfaces, eachincluding at least one electrode, can be configured to be placed againstthe foreign object, the second finger being configured to operate toprovide another electroadhesive force between the electroadhesivegripping surfaces and the foreign object. The various electroadhesivegripping surfaces can be formed from two different sets ofelectroadhesive materials, or can be made from a single monolithicmaterial attached to two different end effectors.

In addition, one or more actuating components, such as a cable driven byan actuator, can be used to couple and control the variouselectroadhesive gripping surfaces or gripping units on each separatecontinuous finger. For example, a first actuating component can becoupled to each of said first plurality of electroadhesive grippingsurfaces, with such a first actuating component being configured to helpposition each of the first plurality of electroadhesive grippingsurfaces with respect to each other and the foreign object.

In various embodiments of the present invention, methods for moving orhandling an object using electroadhesive force are provided. Processsteps can include placing a first electroadhesive gripping surfacehaving at least one electrode against a first surface region of aforeign object, moving a second electroadhesive gripping surface havingat least one electrode with respect to the first electroadhesivegripping surface, placing the second electroadhesive gripping surfaceagainst a second surface region of the foreign object, applying a firstelectrostatic adhesion voltage difference at a plurality of theelectrodes of one or both of said first and second electroadhesivegripping surfaces, and moving the electroadhesive gripping surfaceswhile maintaining substantially the first electrostatic adhesion voltagedifference at the plurality of electrodes so that the object is alsomoved thereby. In some embodiments, the first and second electroadhesivegripping surfaces may be moved and placed simultaneously on the foreignobject. In some embodiments, the electrostatic adhesion voltage may beturned on before the electroadhesive gripping surfaces touch the foreignobject.

Additional process steps can include applying a second electrostaticadhesion voltage difference at a different plurality of the electrodesof one or both of the first and second electroadhesive gripping surfacessuch that a second electrostatic attraction force is created in a seconddirection between one or both of the first and second electroadhesivegripping surfaces and the foreign object. Again, the actuator can beselected from the group consisting of a cable driven by an actuator, anelectromagnetic motor, a stepper motor, a hydraulic system, a pneumaticsystem, a shape memory alloy, and an electroactive polymer, amongothers. Furthermore, each of said first and second electroadhesivegripping surfaces can include a plurality of electrodes, such that eachof said first and second electroadhesive gripping surfaces are adaptedto provide a localized electrostatic adhesion voltage difference attheir respect surface regions of the foreign object.

Other apparatuses, methods, features and advantages of the inventionwill be or will become apparent to one with skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description, be within the scope ofthe invention, and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The included drawings are for illustrative purposes and serve only toprovide examples of possible structures and arrangements for thedisclosed inventive electroadhesive gripping systems and methods. Thesedrawings in no way limit any changes in form and detail that may be madeto the invention by one skilled in the art without departing from thespirit and scope of the invention.

FIG. 1A illustrates in side cross-sectional view an exemplaryelectroadhesive end effector according to one embodiment of the presentinvention.

FIG. 1B illustrates in side cross-sectional view the exemplaryelectroadhesive end effector of FIG. 1A adhered to a foreign objectaccording to one embodiment of the present invention.

FIG. 1C illustrates in side cross-sectional close-up view an electricfield formed in the foreign object of FIG. 1B as result of the voltagedifference between electrodes in the adhered exemplary electroadhesiveend effector according to one embodiment of the present invention.

FIG. 2A illustrates in side cross-sectional view an exemplary pair ofelectroadhesive gripping surfaces or end effectors having singleelectrodes thereon according to one embodiment of the present invention.

FIG. 2B illustrates in side cross-sectional view the exemplary pair ofelectroadhesive gripping surfaces or end effectors of FIG. 2A withvoltage applied thereto according to one embodiment of the presentinvention.

FIG. 3A illustrates in top perspective view an exemplary electroadhesivegripping surface in the form of a sheet with electrodes patterned on topand bottom surfaces thereof according to one embodiment of the presentinvention.

FIG. 3B illustrates in top perspective view an alternative exemplaryelectroadhesive gripping surface in the form of a sheet with electrodespatterned on a single surface thereof according to one embodiment of thepresent invention.

FIG. 4A illustrates in side elevated view an exemplary flatelectroadhesive end effector adapted to utilize a variable voltageaccording to one embodiment of the present invention.

FIG. 4B illustrates in side elevated view the exemplary electroadhesiveend effector of FIG. 4A having a tuned applied voltage and picking uponly a portion of a foreign object according to one embodiment of thepresent invention.

FIG. 5A illustrates in side elevated view an exemplary electroadhesivegripping system having two electroadhesive gripping surfaces suitablefor lifting thin and flexible foreign objects according to oneembodiment of the present invention.

FIG. 5B illustrates in side elevated view the exemplary electroadhesivegripping system of FIG. 5A having its two electroadhesive grippingsurfaces rotated at an angle to minimize peeling according to oneembodiment of the present invention.

FIG. 6A illustrates in top plan view an exemplary spherical orcylindrical foreign object being gripped by traditional mechanicallygripping actuators.

FIG. 6B illustrates in top plan view the foreign object of FIG. 6A beinggripped by electroadhesive gripping surfaces according to one embodimentof the present invention.

FIG. 7A illustrates in side perspective view an exemplary force diagramfor a foreign object being gripped by traditional mechanically grippingactuators.

FIG. 7B illustrates in top plan view the exemplary force diagram for theforeign object of FIG. 7A.

FIG. 7C illustrates in side perspective view an exemplary force diagramfor a foreign object being gripped by electroadhesive gripping surfacesaccording to one embodiment of the present invention.

FIG. 7D illustrates in top plan view the exemplary force diagram for theforeign object of FIG. 7C.

FIG. 8 illustrates in side elevated view an exemplary electroadhesivegripping system having multiple fingers, each having a plurality ofelectroadhesive gripping surfaces thereupon, along with an exemplary setof control circuitry according to one embodiment of the presentinvention.

FIG. 9A illustrates in side elevated view the exemplary electroadhesivegripping system of FIG. 8 as applied to a foreign object having a largeflat surface according to one embodiment of the present invention.

FIG. 9B illustrates in side elevated view the exemplary electroadhesivegripping system of FIG. 8 as applied to a foreign object comprising asmall pin according to one embodiment of the present invention.

FIG. 9C illustrates in top plan view the exemplary electroadhesivegripping system of FIG. 8 as applied to a foreign object comprising amedium sized ball according to one embodiment of the present invention.

FIG. 10 illustrates in front perspective view an exemplary robotic handhaving numerous fingers, electroadhesive gripping surfaces and cableactuators according to one embodiment of the present invention.

FIG. 11A illustrates in side perspective view an exemplary applicationof a wearable glove having multiple electroadhesive gripping surfaceslocated along the outer surfaces according to one embodiment of thepresent invention.

FIG. 11B illustrates in block diagram format an exemplary application ofthe wearable glove of FIG. 11A being used to aid in the gripping of abag strap to carry an associated bag according to one embodiment of thepresent invention.

FIG. 12 provides a flowchart of an exemplary method of gripping anobject using electroadhesive force according to one embodiment of thepresent invention.

DETAILED DESCRIPTION

Exemplary applications of apparatuses and methods according to thepresent invention are described in this section. These examples arebeing provided solely to add context and aid in the understanding of theinvention. It will thus be apparent to one skilled in the art that thepresent invention may be practiced without some or all of these specificdetails. In other instances, well known process steps have not beendescribed in detail in order to avoid unnecessarily obscuring thepresent invention. Other applications are possible, such that thefollowing examples should not be taken as limiting.

In the following detailed description, references are made to theaccompanying drawings, which form a part of the description and in whichare shown, by way of illustration, specific embodiments of the presentinvention. Although these embodiments are described in sufficient detailto enable one skilled in the art to practice the invention, it isunderstood that these examples are not limiting; such that otherembodiments may be used, and changes may be made without departing fromthe spirit and scope of the invention.

The invention relates in various embodiments to an electroadhesivegripping device or system adapted to handle objects and materials. Inparticular, such an electroadhesive gripping system can be adapted tohold, move or even pick and place a wide variety of objects, includingsmall, dirty and/or fragile objects. Such handling can be accomplishedwith minimal mechanical or “crushing” forces from the gripping systemonto the foreign object, due to the use of mostly electroadhesiveforces. In addition to the moving and picking and placement of items,further applications of the provided electroadhesive gripping system arealso possible, such that it will be understood that the providedelectroadhesive gripping system is not limited to use to suchapplications. For example, the same or similar electroadhesive grippingsystem components can be used in a glove to be worn by a user, such asto aid the user in gripping an object despite the onset of arthritis orother weakness. Additional alternative applications may also bepracticed, as will be readily appreciated.

Electroadhesion

As the term is used herein, ‘electroadhesion’ refers to the mechanicalcoupling of two objects using electrostatic forces. Electroadhesion asdescribed herein uses electrical control of these electrostatic forcesto permit temporary and detachable attachment between two objects. Thiselectrostatic adhesion holds two surfaces of these objects together orincreases the traction or friction between two surfaces due toelectrostatic forces created by an applied electric field. Althoughelectrostatic clamping has traditionally been limited to holding twoflat, smooth and generally conductive surfaces together, the presentinvention involves electroadhesion devices and techniques that do notlimit the material properties or surface roughness of the objectssubject to electroadhesive forces and handling.

Turning first to FIG. 1A, an exemplary electroadhesive end effectoraccording to one embodiment of the present invention is illustrated inelevated cross-sectional view. Electroadhesive end effector 10 includesone or more electrodes 18 located at or near an “electroadhesivegripping surface” 11 thereof, as well as an insulating material 20between electrodes and a backing 24 or other supporting structuralcomponent. For purposes of illustration, electroadhesive end effector 10is shown as having six electrodes in three pairs, although it will bereadily appreciated that more or fewer electrodes can be used in a givenelectroadhesive end effector. Where only a single electrode is used in agiven electroadhesive end effector, a complimentary electroadhesive endeffector having at least one electrode of the opposite polarity ispreferably used therewith. With respect to size, electroadhesive endeffector 10 is substantially scale invariant. That is, electroadhesiveend effector sizes may range from less than 1 square centimeter togreater than several meters in surface area. Even larger and smallersurface areas also possible, and may be sized to the needs of a givenapplication.

FIG. 1B depicts in elevated cross-sectional view the exemplaryelectroadhesive end effector 10 of FIG. 1A adhered to a foreign object14 according to one embodiment of the present invention. Foreign object14 includes surface 12 and inner material 16. Electroadhesive grippingsurface 11 of electroadhesive end effector 10 is placed against ornearby surface 12 of foreign object 14. An electrostatic adhesionvoltage is then applied via electrodes 18 using external controlelectronics (not shown) in electrical communication with the electrodes18. As shown in FIG. 1B, the electrostatic adhesion voltage usesalternating positive and negative charges on neighboring electrodes 18.As result of the voltage difference between electrodes 18, one or moreelectroadhesive forces are generated, which electroadhesive forces actto hold the electroadhesive end effector 10 and foreign object 14against each other. Due to the nature of the forces being applied, itwill be readily appreciated that actual contact between electroadhesiveend effector 10 and foreign object 14 is not necessary. For example, apiece of paper, thin film, or other material or substrate may be placedbetween electroadhesive end effector 10 and foreign object 14.Furthermore, although the term “contact” is used herein to denote theinteraction between an electroadhesive end effector and a foreignobject, it will be understood that actual direct surface to surfacecontact is not always required, such that one or more thin objects suchas an insulator, can be disposed between an end effector orelectroadhesive gripping surface and the foreign object. In someembodiments such an insulator between the gripping surface and foreignobject can be a part of the end effector, while in others it can be aseparate item or device.

FIG. 1C illustrates in elevated cross-sectional close-up view anelectric field formed in the foreign object of FIG. 1B as result of thevoltage difference between electrodes in the adhered exemplaryelectroadhesive end effector 10. While the electroadhesive end effector10 is placed against foreign object 14 and an electrostatic adhesionvoltage is applied, an electric field 22 forms in the inner material 16of the foreign object 14. The electric field 22 locally polarizes innermaterial 16 or induces direct charges on material 16 locally opposite tothe charge on the electrodes of the end effector 18 and thus causeselectrostatic adhesion between the electrodes 18 (and end effector 10)and the induced charges on the foreign object 16. The induced chargesmay be the result of a dielectric polarization or from weakly conductivematerials and electrostatic induction of charge. In the event that theinner material 16 is a strong conductor, such as copper for example, theinduced charges may completely cancel the electric field 22. In thiscase the internal electric field 22 is zero, but the induced chargesnonetheless still form and provide electrostatic force to theelectroadhesive end effector.

Thus, the electrostatic adhesion voltage provides an overallelectrostatic force, between the electroadhesive end effector 10 andinner material 16 beneath surface 12 of foreign object 14, whichelectrostatic force maintains the current position of theelectroadhesive end effector relative to the surface of the foreignobject. The overall electrostatic force may be sufficient to overcomethe gravitational pull on the foreign object 14, such that theelectroadhesive end effector 10 may be used to hold the foreign objectaloft. In various embodiments, a plurality of electroadhesive endeffectors may be placed against foreign object 14, such that additionalelectrostatic forces against the object can be provided. The combinationof electrostatic forces may be sufficient to lift, move, pick and place,or otherwise handle the foreign object. Electroadhesive end effector 10may also be attached to other structures and hold these additionalstructures aloft, or it may be used on sloped or slippery surfaces toincrease normal friction forces

Removal of the electrostatic adhesion voltages from electrodes 18 ceasesthe electrostatic adhesion force between electroadhesive end effector 10and the surface 12 of foreign object 14. Thus, when there is noelectrostatic adhesion voltage between electrodes 18, electroadhesiveend effector 10 can move more readily relative to surface 12. Thiscondition allows the electroadhesive end effector 10 to move before andafter an electrostatic adhesion voltage is applied. Well controlledelectrical activation and de-activation enables fast adhesion anddetachment, such as response times less than about 50 milliseconds, forexample, while consuming relatively small amounts of power.

Electroadhesive end effector 10 includes electrodes 18 on an outsidesurface 11 of an insulating material 20. This embodiment is well suitedfor controlled attachment to insulating and weakly conductive innermaterials 14 of various foreign objects 16. Other electroadhesive endeffector 10 relationships between electrodes 18 and insulating materials20 are also contemplated and suitable for use with a broader range ofmaterials, including conductive materials. For example, a thinelectrically insulating material (not shown) can be located on thesurfaces of the electrodes where surface 12 is on a metallic object. Aswill be readily appreciated, a shorter distance between surfaces 11 and12 results in a stronger electroadhesive force between the objects.Accordingly, a deformable surface 11 adapted to at least partiallyconform to the surface 12 of the foreign object 14 can be used.

As the term is used herein, an electrostatic adhesion voltage refers toa voltage that produces a suitable electrostatic force to coupleelectroadhesive end effector 10 to a foreign object 14. The minimumvoltage needed for electroadhesive end effector 10 will vary with anumber of factors, such as: the size of electroadhesive end effector 10,the material conductivity and spacing of electrodes 18, the insulatingmaterial 20, the foreign object material 16, the presence of anydisturbances to electroadhesion such as dust, other particulates ormoisture, the weight of any objects being supported by theelectroadhesive force, compliance of the electroadhesive device, thedielectric and resistivity properties of the foreign object, and therelevant gaps between electrodes and foreign object surface. In oneembodiment, the electrostatic adhesion voltage includes a differentialvoltage between the electrodes 18 that is between about 500 volts andabout 10 kilovolts. Even lower voltages may be used in microapplications. In one embodiment, the differential voltage is betweenabout 2 kilovolts and about 5 kilovolts. Voltage for one electrode canbe zero. Alternating positive and negative charges may also be appliedto adjacent electrodes 18. The voltage on a single electrode may bevaried in time, and in particular may be alternated between positive andnegative charge so as to not develop substantial long-term charging ofthe foreign object. The resultant clamping forces will vary with thespecifics of a particular electroadhesive end effector 10, the materialit adheres to, any particulate disturbances, surface roughness, and soforth. In general, electroadhesion as described herein provides a widerange of clamping pressures, generally defined as the attractive forceapplied by the electroadhesive end effector divided by the area thereofin contact with the foreign object

The actual electroadhesion forces and pressure will vary with design anda number of factors. In one embodiment, electroadhesive end effector 10provides electroadhesive attraction pressures between about 0.7 kPa(about 0.1 psi) and about 70 kPa (about 10 psi), although other amountsand ranges are certainly possible. The amount of force needed for aparticular application may be readily achieved by varying the area ofthe contacting surfaces, varying the applied voltage, and/or varying thedistance between the electrodes and foreign object surface, althoughother relevant factors may also be manipulated as desired.

Because an electrostatic adhesion force is the primary force used tohold, move or otherwise manipulate a foreign object, rather than atraditional mechanical or “crushing” force, the electroadhesive endeffector 10 can be used in a broader set of applications. For example,electroadhesive end effector 10 is well suited for use with roughsurfaces, or surfaces with macroscopic curvature or complex shape. Inone embodiment, surface 12 includes roughness greater than about 100microns. In a specific embodiment, surface 12 includes roughness greaterthan about 3 millimeters. In addition, electroadhesive end effector 10can be used on objects that are dusty or dirty, as well as objects thatare fragile. Objects of varying sizes and shapes can also be handled byone or more electroadhesive end effectors, as set forth in greaterdetail below. Various additional details and embodiments regardingelectroadhesion and applications thereof can be found at, for example,commonly owned U.S. Pat. Nos. 7,551,419 and 7,554,787, which areincorporated by reference herein in their entirety and for all purposes.

Electroadhesive Gripping Surfaces

Although electroadhesive end effector 10 having electroadhesive grippingsurface 11 of FIG. 1A is shown as having six electrodes 18, it will beunderstood that a given electroadhesive end effector or gripping surfacecan have just a single electrode. Furthermore, it will be readilyappreciated that a given electroadhesive end effector can have aplurality of different electroadhesive gripping surfaces, with eachseparate electroadhesive gripping surface having at least one electrodeand being adapted to be placed against or in close proximity to theforeign object to be gripped. Although the terms electroadhesive endeffector, electroadhesive gripping unit and electroadhesive grippingsurface are all used herein to designate electroadhesive components ofinterest, it will be understood that these various terms can be usedinterchangeably in various contexts. In particular, while a given “endeffector” might comprise numerous distinct “gripping surfaces,” thesedifferent gripping surfaces might also be considered separate endeffectors themselves. While the robotic hand embodiment of FIG. 10 mightbe considered as one single end effector having numerous differentgripping surfaces, for example, this robotic hand could also beconsidered as numerous different end effectors acting in concert.

Referring to FIGS. 2A and 2B, an exemplary pair of electroadhesive endeffectors or gripping surfaces having single electrodes thereon is shownin side cross-sectional view. FIG. 2A depicts electroadhesive grippingsystem 100 having electroadhesive end effectors or gripping surfaces 30,31 that are in contact with the surface of a foreign object 16, whileFIG. 2B depicts activated electroadhesive gripping system 100′ with theend effectors or gripping surfaces having voltage applied thereto.Electroadhesive gripping system 100 includes two electroadhesive endeffectors or gripping surfaces 30, 31 that directly contact the foreignobject 16. Each electroadhesive end effector or gripping surface 30, 31has a single electrode 18 coupled thereto. In such cases, theelectroadhesive gripping system can be designed to use the foreignobject as an insulation material. When voltage is applied, an electricfield 22 forms within foreign object 14, and an electrostatic forcebetween the electroadhesive end effectors or gripping surfaces 30, 31and the foreign object is created. Various embodiments that includenumerous of these single electrode electroadhesive end effectors can beused, as will be readily appreciated.

In some embodiments, an electroadhesive gripping surface can take theform of a flat panel or sheet having a plurality of electrodes thereon.In other embodiments, the gripping surface can take a fixed shape thatis matched to the geometry of the foreign object most commonly lifted orhandled. For example, a curved geometry can be used to match thegeometry of a cylindrical paint can or soda can. The electrodes may beenhanced by various means, such as by being patterned on an adhesivedevice surface to improve electroadhesive performance, or by making themusing soft or flexible materials to increase compliance and thusconformance to irregular surfaces on foreign objects. Turning next toFIGS. 3A and 3B, two examples of electroadhesive gripping surfaces inthe form of flat panels or sheets with electrodes patterned on surfacesthereof are shown in top perspective view. FIG. 3A shows electroadhesivegripping surface 200 in the form of a sheet or flat panel withelectrodes 218 patterned on top and bottom surfaces thereof. Top andbottom electrodes sets 240 and 242 are interdigitated on opposite sidesof an insulating layer 244. In some cases, insulating layer 244 can beformed of a stiff or rigid material. In some cases, the electrodes aswell as the insulating layer 244 may be compliant and composed of apolymer, such as an acrylic elastomer, to increase compliance. In onepreferred embodiment the modulus of the polymer is below about 10 MPaand in another preferred embodiment it is more specifically below about1 MPa. Various types of compliant electrodes suitable for use with thepresent invention are generally known, and examples are described incommonly owned U.S. Pat. No. 7,034,432, which is incorporated byreference herein in its entirety and for all purposes.

Electrode set 242 is disposed on a top surface 223 of insulating layer244, and includes an array of linear patterned electrodes 218. A commonelectrode 241 electrically couples electrodes 218 in set 242 and permitselectrical communication with all the electrodes 218 in set 242 using asingle input lead to common electrode 241. Electrode set 240 is disposedon a bottom surface 225 of insulating layer 244, and includes a secondarray of linear patterned electrodes 218 that is laterally displacedfrom electrodes 218 on the top surface. Bottom electrode set 240 mayalso include a common electrode (not shown). Electrodes can be patternedon opposite sides of an insulating layer 244 to increase the ability ofthe electroadhesive end effector 200 to withstand higher voltagedifferences without being limited by breakdown in the air gap betweenthe electrodes, as will be readily appreciated.

Alternatively, electrodes may also be patterned on the same surface ofthe insulating layer, such as that which is shown in FIG. 3B. As shown,electroadhesive gripping surface 300 comprises a sheet or flat panelwith electrodes 318 patterned only on one surface thereof.Electroadhesive gripping surface 300 can be substantially similar toelectroadhesive gripping surface 200 of FIG. 3A, except that electrodessets 346 and 348 are interdigitated on the same surface 323 of acompliant insulating layer 344. No electrodes are located on the bottomsurface 325 of insulating layer 344. This particular embodimentdecreases the distance between the positive electrodes 318 in set 346and negative electrodes 318 in set 348, and allows the placement of bothsets of electrodes on the same surface of electroadhesive grippingsurface 300. Functionally, this eliminates the spacing between theelectrodes sets 346 and 348 due to insulating layer 344, as inembodiment 200. It also eliminates the gap between one set of electrodes(previously on bottom surface 125) and the foreign object surface whenthe top surface 323 adheres to the foreign object surface. Althougheither embodiment 200 or 300 can be used, these changes in the latterembodiment 300 do increase the electroadhesive forces betweenelectroadhesive gripping surface 300 and the subject foreign object tobe handled.

In some embodiments, an electroadhesive end effector or gripping surfacemay comprise a sheet or veil type grasper that is substantially flexiblein nature. In such embodiments, either no backing structure or asubstantially flexible backing structure can be used, such that all or aportion of the veil type end effector or gripping surface cansubstantially flex or otherwise conform to a foreign object or objects,as may be desired for a given application. Creating electroadhesive endeffectors that facilitate such conforming or compliance to a foreignobject can be achieved, for example, by forming the electroadhesivelayer or gripping surface out of thin materials, by using foam orelastic materials, by butting out flaps or extensions from a primaryelectroadhesive sheet, or by applying the sheet only to a few selectedunderlying locations, rather than to an entire rigid backing, amongother possibilities.

Although the foregoing exemplary embodiments for electroadhesivegripping surfaces in the form of flat panels or sheets depict bars orstripes for electrodes, it will be understood that any suitable patternfor electrodes could also be used for such a sheet-type electroadhesivegripping surface. For example, a sheet-type electroadhesive grippingsurface could have electrodes in the form of discrete squares or circlesthat are distributed about the sheet and polarized in an appropriatemanner, such as in an evenly spaced “polka-dot” style pattern. Otherexamples such as two sets of electrodes patterned as offset spirals, canalso be used. As one particular example, where a thin and flexiblematerial is used for the insulating layer, such as a polymer, and whereelectrodes are distributed thereabout in the form of discrete discs, aresulting flexible and compliant electroadhesive gripping surface“blanket” would be able to conform to the irregular surfaces of arelatively large object while providing numerous different and discreteelectroadhesive forces thereto during voltage application.

Penetration Depth Tuning

Fine control of the amount of voltage to the electrodes in a givensingle or set of electroadhesive end effectors can significantly affectthe handling of foreign objects thereby. Varying the voltage to theelectrodes results in varying the applied electrostatic orelectroadhesive force between an electroadhesive end effector and anobject to be handled. Such variances in the overall electroadhesiveforce applied to a foreign object can result in certain beneficialresults, such as only a portion of the object being lifted, held ormoved. A simple example of varying the amount of voltage toelectroadhesive end effector electrodes to affect a result can involveflat panel or sheet-type end effectors used to pick up a stack of paper.Variances in the electroadhesive force can also be used to controllablyslide objects relative to the end effector. Such controlled sliding isespecially useful when repositioning objects within a grip such asrepositioning a pen within a grip, or rotating a cuboid shaped objectinside a robotic hand.

Continuing with FIGS. 4A and 4B, an exemplary flat electroadhesive endeffector adapted to utilize a variable voltage according to oneembodiment of the present invention in illustrated in side elevatedview. Electroadhesive gripping system 400 includes a flatelectroadhesive end effector 410 having a plurality of electrodes 418disposed on at least one gripping surface thereof, as well as a handle401, bar or other tool that enables the manipulation of the end effectorby a user or machine. Electroadhesive end effector 410 can include, forexample, one of the flat panel or sheet-type electroadhesive grippingsurfaces 200, 300 described above, although other variations for an endeffector are also certainly possible. A stack of paper 414 representsthe object to be handled by electroadhesive gripping system 400.

From its position in FIG. 4A, electroadhesive end effector 410 islowered onto the stack of paper 414 and voltage is applied to the endeffector. Once the appropriate level of voltage is applied andmaintained, the electroadhesive end effector 410 is then lifted, asshown in modified electroadhesive gripping system 400′ in FIG. 4B. Stackof paper 414 is then separated into two parts, lifted portion 414 a andremaining portion 414 b. As shown, lifted stack of paper 414 a includesexactly four sheets of paper, while the remaining sheets are not lifted.The number of sheets that are lifted is dependent upon the “penetrationdepth” of the electroadhesive force, which is related to a number offactors.

Again, such factors can include applied voltage, the amount of surfacearea contact, electroadhesive end effector size, electrode materialconductivity and spacing, insulating material composition, foreignobject material composition, gap distance between electrodes and theforeign object, and the presence of dust, moisture or other disturbancesto electroadhesion, among others. Of all such factors though, the amountof applied voltage is one that is particularly controllable. As such,the amount of voltage that is applied to electrodes 418 can be varied orprecisely “tuned” such that a desired exact number of sheets of paperare lifted.

In the example of FIGS. 4A and 4B, when no voltage is applied to theelectrodes 418, then electroadhesive end effector 410 does not pick upor manipulate any of the paper stack 414. When a low voltage (V1) isapplied to the electroadhesive end effector 410, then exactly one sheetof paper can be reliably picked up or moved around from the stack ofpaper 414. When a slightly higher voltage (V2) is applied, then exactlytwo sheets of paper can be similarly manipulated. When an even highervoltage is applied (V3), even more sheets can be picked up, such as thefour sheets 414 a shown in FIG. 4B. Further variations in the appliedvoltage can then be used to pick up different amounts of paper sheets.

Potential enhancements can include using such electroadhesion along withan active circuit that tunes the voltage, while simultaneously measuringcapacitance to determine the actual number of sheets of paper that arecoupled to the electroadhesive end effector. Rise time for the voltagecan also be monitored as an indirect measure of capacitance, and thevoltage can be tuned accordingly. Other measures to measure or quantifynumber of sheets lifted, such as mechanical thickness of the stack thatis picked up, can also be used in a feedback loop to control theelectroadhesive voltage.

Potential uses can include the handling of paper in printers, copiers,facsimile machines and the like, and even in industrial paper handlingequipment, such as ATM machines or other machines handling bills ornotes. Other applications can include handling sheets of laminates, suchas for countertops, for example. One of skill in the art will readilyappreciate the extrapolation of this concept to other more complexforeign objects, such that under one voltage an entire foreign objectcan be lifted, moved or otherwise manipulated, while under another lowervoltage only a part or component of that foreign object is similarlymoved or manipulated. Lowering the voltage in one part of a givenelectroadhesive gripping surface or end effector while maintaininghigher voltage in another part also allows pivoting or repositioning theobject within the grasp without requiring very fin control of themechanical position and forces applied to the object.

Peeling Resistance

One drawback to the use of electroadhesion, such as that which is setforth in the foregoing examples, is the tendency for a peeling orfalling away effect at the edges of the contact surface areas where anelectroadhesive end effector or gripping surface and foreign object orsubstrate meet. In some cases, the gripping surface can utilize aproperty of lower electroadhesive peel forces, especially during therelease of an object after relocating or reorienting it to a newposition to enhance the speed of release or to ensure completedetachment of the object. In many other cases, however, the lowerpeeling force is an important design consideration for optimalperformance of the end effector or gripping surface. This can beparticularly true for instances where objects extend and havesignificant weight beyond the edges of the electroadhesive end effectoror gripping surface, such as in the foregoing paper lifting example ofFIGS. 4A and 4B. Various modifications and techniques can be used tocounteract or diminish such peeling effects.

Turning now to FIG. 5A, an exemplary electroadhesive gripping systemhaving two electroadhesive gripping surfaces suitable for liftingflexible foreign objects is shown in side elevated view. Electroadhesivegripping system 500 includes two electroadhesive end effectors orgripping surfaces 510 a, 510 b arranged at a distance with respect toeach other, and each having its own separate handle 501 a, 501 b orother device to facilitate lifting or handling. This arrangementgenerally means that the different “a” and “b” items belong to differentelectroadhesive end effectors, as will be readily appreciated. Such anarrangement can enable the system 500 to lift or handle relatively largeobjects or materials, such as large sheets of paper, fabric, prepreg orthe like. For purposes of illustration, system 500 can be arranged tolift and move a sheet of prepreg material 514 from a stack of suchmaterials. The weight of such a material, particular at its outer edges,can cause a peeling effect.

Under regular use, both electroadhesive end effectors (or grippingsurfaces) 510 a, 510 b are lowered to contact the surface of sheet 514.That is, a first electroadhesive end effector 501 a contacts a firstsurface region of sheet or other foreign object 514 such that a firstline 503 a normal to a first surface of contact between the firstelectroadhesive end effector 501 a and the sheet 514 is created.Similarly, a second electroadhesive end effector 501 b contacts a secondseparate surface region of sheet 514 such that a second line 503 bnormal to a second surface of contact between the second electroadhesiveend effector 501 b and the sheet 514 is created. Under regular use, suchas where the stack of sheets produces a relatively flat upper surface,this results in a placement of electroadhesive end effectors such thatthe first normal line 503 a and the second normal line 503 b aresubstantially parallel in nature, as shown in FIG. 5A. Alternatively, itcan be considered that the first and second surfaces of contact liesubstantially within the same plane.

As noted, one possible undesirable result from such an arrangement isthat sheet 514 can tend to peel away from the edges of the endeffectors. For example, while there is little to no peeling or gap 502 aat the outer edge of electroadhesive end effector 510 a, the otherelectroadhesive end effector 510 b may experience some peeling at itsouter edge, such as that seen at gap 502 b. Of course, some instancesmay involve peeling at both edges, other instance may involve peeling atthe inner edges of each end effector as well, while still others mayinvolve no peeling at all. In any event, such peeling is undesirable,since the resulting reduction in force at the precise location where thesurfaces of both objects diverge may lead to the precipitation of evenfurther peeling. In some instances, the entire foreign object may bepeeled away from the electroadhesive end effector once peeling starts.

One technique for dealing with peeling is to rotate the electroadhesiveend effectors or gripping surfaces. FIG. 5B illustrates in side elevatedview the exemplary electroadhesive gripping system of FIG. 5A having itstwo electroadhesive end effectors or gripping surfaces rotated at anangle so as to minimize peeling. In modified electroadhesive grippingsystem 500′, both electroadhesive end effectors 510 a, 510 b have beenrotated outward somewhat, such that the normal lines 503 a′, 503 b′ areno longer parallel to each other. Alternatively, it can be consideredthat the first and second surfaces of contact do not lie substantiallywithin the same plane. Although the amount of rotation on each endeffector is definitely noticeable as shown, it is also contemplated thatsuch an amount of rotation can be lessened without losing the benefitsof such an arrangement. By rotating the electroadhesive end effectorssuch that their respective normal lines are no longer parallel (orsurfaces of contact do not lie within the same plane), the relativelyflexible material of sheet 514 can be pulled taut or otherwise have anyslack therein reduced. This in turn reduces the tendency of the materialto peel away from the edges of the electroadhesive end effectors,particularly at the inside edges.

Another technique that can be used to combat peeling is to vary thevoltages to different electrodes, in the event that each electroadhesiveend effector has a plurality of electrodes. Under such an arrangement,more voltage can be delivered to the outer electrodes near the outeredge of an electroadhesive end effector (i.e., near gaps 502 a and 502b), than is delivered to other electrodes. This arrangement can beparticularly beneficial where a finely tuned voltage is being used topick up an exact number of sheets, but peeling of the sheets away fromthe outer edges of the end effectors is to be eliminated or minimized

Yet another technique is to vary the distance or tension between thegripping surfaces, such that a mechanical force is applied to keep thesheet 514 taut and minimize droop or peeling forces. Other techniques tomitigate peeling forces include the addition of geometrical features tothe electroadhesive gripping surface of one or more end effectors 502 aand 502 b. Such geometrical features may include cutting flaps out ofthe electroadhesive gripping surface, or the addition of fibers orhair-like structures to the electroadhesive gripping surface.

Gripping

Although the foregoing examples have been limited to foreign objectshaving flat surfaces, particularly thin sheets and the like, a widevariety of different foreign objects can be gripped and handled throughthe use of such electroadhesive end effectors. In particular, thestrategic use of multiple electroadhesive end effectors can overcomemany of the drawbacks associated with traditional mechanical pick andplace processes, such as for robotics or other manufacturingapplications.

Moving to FIG. 6A, an exemplary spherical or cylindrical foreign objectbeing gripped by traditional mechanically gripping actuators isillustrated in top plan view. Mechanical gripping system 600 includesfour mechanical gripping actuators or components 605 a, 605 b, 605 c,605 d placed at various different surface locations of foreign object614. Because mechanical “crushing” forces are used to grip and handlethe foreign object 614, it is typical for the various actuators 605 tobe located on opposite sides of the object from each other. In order forthe object 614 to be gripped and handled, each actuator exerts asignificant mechanical crushing or squeezing force, 606 a, 606 b, 606 c,606 d on the object. These mechanical forces 606 are preferablysufficient to overcome the weight of the object, and each mechanicalforce component needs an opposing force component on an opposing side ofthe object in order to adequately grip the object. This traditionalmechanical gripping process can be disturbed or discouraged by numerousfactors, including a dirty or wet object, surface irregularities, afragile or delicate object, or an inability to locate adequately themechanical actuators on opposing sides of the object to effectivelybalance the forces, among others.

FIG. 6B illustrates in top plan view the foreign object of FIG. 6A beinggripped by two electroadhesive gripping surfaces according to oneembodiment of the present invention. Electroadhesive gripping system 650includes just two actuators in the form of electroadhesive grippingsurfaces 610 a, 610 b, which can be placed at a variety of locationsabout the surface of foreign object 614. In significant contrast tomechanical gripping system 600, the electroadhesive gripping surfaces610 a, 610 b do not need to oppose each other in magnitude or be onopposite sides of the object 614. This is primarily becauseelectroadhesive forces are used rather than mechanical crushing forcesto grip the object. As such, the force exerted by one electroadhesivegripping surface on the foreign object does not need to be countered byan opposing force on the opposite side of the object. As shown,electroadhesive gripping surfaces can be placed at a 90 degree anglewith respect to each other about the surface of object 614, for example.A wide variety of relative locations and placements can also be used, aswill be readily appreciated. Such freedom in actuator placement is asubstantial advantage over traditional mechanical systems.

Another significant difference between mechanical gripping system 600and electroadhesive gripping system 650 is that less overall force isneeded to grip and handle the foreign object 614 in an electroadhesivesystem. While mechanical crushing or pinching forces need to oppose eachother, such as force 606 a opposite force 606 d and force 606 b oppositeforce 606 c in the mechanical gripping system 600, no such opposingmechanical force components are needed for electroadhesive forces 613 aand 613 b in the electroadhesive gripping system 650.

Referring to FIGS. 7A-7D, various force diagrams with respect to anexemplary cylindrical foreign object demonstrate the differences inapplied forces between a traditional mechanical gripping system and theinventive electroadhesive gripping system disclosed herein. Startingwith FIG. 7A, an exemplary force diagram for a foreign object beinggripped by traditional mechanically gripping actuators is shown in sideperspective view. Mechanical gripping system 700 must overcome or offsetthe weight W of foreign object 714 in order to handle the object. Forpurposes of illustration, three incumbent mechanical forces 706 a, 706b, 706 c representing forces from three mechanically gripping actuatorsare shown. It will be readily appreciated that more mechanical actuatorscould be used, or alternatively, that exactly two diametrically opposingmechanical actuators could be used.

Each of incumbent mechanical forces 706 a, 706 b, 706 c imparts anupward frictional force against their respective surface areas offoreign object 714, which upward frictional forces are naturally afraction of the directly imparted crushing forces. These frictionalforces are dependent upon a coefficient of friction “f,” and arerepresented as f*706(x). For the weight of the object 714 to be overcomeby mechanical gripping system 700, the sum of (f*706 a)+(f*706 b)+(f*706c) must be greater than W. Of course, the coefficient of friction f canvary widely depending upon the textures and conditions of the contactingsurfaces. Where an object is relatively slippery, this coefficient f issmall, which then results in the need for even greater incumbent forcesto overcome the object weight. This results in mechanical forces 706 a,706 b, 706 c that can be relatively large.

FIG. 7B illustrates in top plan view the exemplary force diagram for theforeign object of FIG. 7A. Again, the sum of all incumbent mechanicalforces 706 a, 706 b, 706 c in the x and y directions against foreignobject 714 must be zero for the object to be mechanically gripped, whichis why these forces are primarily “crushing” forces. As shown, force 706a lies completely in the x direction, such that the sum of x directioncomponents of forces 706 b and 706 c must offset force 706 a. Becauseforce 706 a has no y direction component in the figure as shown, the ydirection components for forces 706 b and 706 c must offset each other.Other arrangements with more or fewer mechanical actuators in varyingdirections may be used, although the final result should require a zerosum of incumbent mechanical forces in the x and y directions. Becausesuch a zero sum force is needed, the positioning of mechanical actuatorscan be particularly critical. Even a slight offset or misplacement ofone mechanical gripping actuator or “finger” can result in a non-zerosum force between actuators, such that the part or object is dropped orotherwise mishandled.

In contrast, FIG. 7C illustrates an exemplary force diagram for aforeign object being gripped by electroadhesive gripping surfacesaccording to one embodiment of the present invention, similarly in sideperspective view. Similar to the mechanical gripping system above,electroadhesive gripping system 750 must overcome or offset the weight Wof foreign object 714 in order to handle the object. Unlike themechanical gripping system, however, this electroadhesive grippingsystem 750 does not rely on mechanical crushing or pinching forces, suchthat precise positioning or offsetting of actuators is not necessary.Rather, system 750 uses a plurality of electroadhesive forces 713 a, 713b, 713 c to grip and handle foreign object 714 using electroadhesivegripping surfaces.

Each of electroadhesive forces 713 a, 713 b, 713 c results in an upwardanti-slip force Px (obtained by multiplying friction coefficient f withthe electroadhesive normal forces) against their respective surfaceareas of foreign object 714. For the weight of the object 714 to beovercome by electroadhesive gripping system 750, the sum of Pa+Pb+Pcmust be greater than W. Of course, the amount of pressure force exertedupward on foreign object 714 is related to numerous factors, includingthe magnitude of electroadhesive force in particular. It is worthnoting, however, that the amount of electroadhesive forces needed tosupport the weight W of foreign object 714 is substantially less thanthe amount of mechanical pinching force to support the same object andweight.

FIG. 7D illustrates in top plan view the exemplary force diagram for theforeign object of FIG. 7C. To the extent that any nominal mechanicalcrushing force is used by the applied electroadhesive end effectors orgripping surfaces, such relatively small mechanical forces must arriveat a zero sum in the x and y directions, similar to that which is setforth above for mechanical gripping system 700. It is worth noting,however, that in many cases, the electroadhesive forces are sufficientto hold the entire weight of the object with no mechanical crushingforces, which supports the object weight in the z-direction, but removesthe need for force balancing in x and y directions.

Numerous drawbacks and issues experienced in conventional mechanicalgripping systems, such as system 700, are overcome or minimized whenusing an electroadhesive gripping system, such as system 750. Forexample, a conventional mechanical gripping system typically requiresintensive sensing and control in order to grip objects reliably withoutdamaging them. Such mechanical gripping systems also tend to requirerelatively large actuators that are sized for the highest expectedgripping forces. These large actuators need to be both precise andpowerful in order to be able to handle delicate objects without slippingor damaging the objects. These requirements tend to result in largeractuators, which in turn results in heavy grippers, which then resultsin higher weights in upstream actuators, all of which impacts theoverall weight and energy usage of the entire robot or system.

In contrast, an electroadhesive gripping system does not require a“closed chain placement” or offsetting of actuators, end effectors orgripping surfaces, such that precise positioning to offset for pinchingforces is not required. Intensive sensing and control for such precisepositioning is thus not needed. Because the anti-slip forces needed tosupport the weight of handled objects comes from electroadhesive forcesrather than pinching forces, actuators or electroadhesive grippingsurfaces can be sized for position control with respect to expectedtasks. The relaxed size, actuation and position control requirements forsuch an electroadhesive gripping system can result in a tenfold savingsin weight and energy consumption while still providing more reliablegripping and handling of the same foreign objects.

For purposes of comparison, a commercial off the shelf humanoidmechanical gripper weighing about 2 kg can have a typical gripping orpinching force of about 5-10 N and corresponding torques of about 0.5-1Nm. The energy required to lift the mechanical actuators 1 meter isabout 20 J. In contrast, equal adhesion forces can be delivered byelectroadhesive end effectors having electroadhesive pads or grippingsurfaces with effective areas of about 2 cm by 5 cm. The electroadhesivepads and associated power supply for such a device could weigh as littleas 30 g. Since the overall end effectors need only be designed forposition control, the overall weight of the electroadhesive endeffectors can be under 200 g. Thus, the energy required to lift thesecomponents by the same height is 1/10 the energy required for aconventional mechanical gripping system. Of course, the energy gain fromweight savings for downstream actuators and components would be evengreater.

Exemplary Applications

The ability to freely move and position gripping actuators in the formof electroadhesive end effectors with respect to a handled foreignobject opens up many new possibilities and designs for object handling.Turning next to FIG. 8, an exemplary electroadhesive gripping systemhaving multiple electroadhesive gripping surface lined fingers andassociated control circuitry is shown in side elevated view.Electroadhesive gripping system 800 includes a first finger 870 a and asecond finger 870 b, with each finger having a plurality of segmentsthat are configured to move with respect to each other. While firstfinger 870 a includes segments 810 a, 810 b and 810 c, second finger 870b includes segments 810 d, 810 e and 810 f. Although only two fingers870 a, 870 b have been shown for purposes of illustration, it will beunderstood that any number of additional fingers may also be used. Eachfinger 870 a, 870 b can extend from a base robot or machine component,such as base components 872 a and 872 b respectively. It will beappreciated that a wide variety of well known robotic and machineapplications can apply to such base components 872 a, 872 b and therobotic or machine components behind them, and such details involvingthese components and upstream thereof are not of special focus here.

A finger segment 810 x can have one or more electroadhesive grippingsurfaces situated thereon. For purposes of illustration, however, justone electroadhesive gripping surface has been included with each fingersegment. In fact, a magnified view of finger segment 810 b is provided,wherein it is clear that a single electroadhesive gripping surface isincluded therein. Similar to the original embodiment 10 from FIG. 1A,finger segment 810 b includes a structural backing 824 and an insulatingmaterial 820 around a plurality of electrodes 818 located at a frontgripping surface thereof. In this embodiment, as in each of the aboveembodiments, each electroadhesive end effector can rely on electricalcontrol and input.

At the very least, a minimum amount of circuitry is needed to provideelectrostatic adhesion voltages to an electroadhesive gripping surface,such as, for example, a control and conditioning circuitry 860 suitablefor providing an appropriate electrostatic adhesion voltage toelectrodes 818 of electroadhesive gripping surface 810 b. Such voltagescan be provided, for example, by a conductive connector 868 between thecontrol and conditioning circuitry and a common or connecting backelectrode (not shown) on the electroadhesive gripping surface 810 b.Control circuitry 862 can be configured to determine when a suitableelectrostatic adhesion voltage is applied to electrodes 818. Controlcircuitry 862 may include a processor or controller that provides on/offsignals that determine when electrostatic adhesion voltages are applied,and what magnitudes. Control circuitry 862 may also determine the timesand timing associated with a charge and discharge cycle on theelectroadhesive end effector 810 b.

Conditioning circuitry 864 may include any circuitry configured toperform one or more of the following tasks: voltage step-up, which isused when applying a voltage to the electrodes 818, conversion betweenAC and DC power, voltage smoothing, and recovery of stored electrostaticenergy. Conditioning circuitry 864 may be designed to receive power froma low-voltage battery 866, for example, or another suitable powersource. For example, in robotics applications, conditioning circuitry864 may receive a voltage from a conventional battery, such as thoseless than 40 volts, and increase the voltage to an electrostaticadhesion voltage above 1 kilovolt. The low voltage power source such asthe battery may be replaced by another electrical source such as a setof small photovoltaic panels similar to the ones used in many handheldcalculators. In one embodiment, conditioning circuitry 864 includes atransformer configured to provide voltage step-up to electrostaticadhesion voltages described herein. More complex charge control circuitsmay be developed, as will be readily appreciated, and are not limited tothe shown design. Also, some of the circuit functions may be integrated.For instance, one integrated circuit may perform the functions of boththe step-up circuitry 864 and the charge control circuitry 862. Aseparate set of circuitry can be included for each electroadhesive endeffector, or a common set of circuitry could be used to control multipleor all electroadhesive end effectors, as may be desired.

Electroadhesive gripping surfaces 810 x can be coupled to each otherand/or a base robot or other machine mechanically by hinges 874 or othersuitable coupling devices. In some embodiments, a flexible supportbacking or skin (not shown) can be used to couple the variouselectroadhesive gripping surfaces, either in addition to or in place ofhinges 874. Such a flexible support backing coupler can be, for example,a polymer such as an acrylic elastomer or foam. Such a polymer can be acompliant electroactive polymer adapted to aid in the positioning of thegripping surfaces or end effectors, with examples again being describedin commonly owned U.S. Pat. No. 7,034,432, as referenced above andincorporated herein. Other actuating devices, such as a cable actuator,suitable for positioning and/or supporting the various electroadhesivegripping surfaces are discussed further below.

The use of multiple continuous fingers 870 a, 870 b, each having aplurality of electroadhesive gripping surfaces 810 x that can be movedwith respect to each other, takes advantage of the noted ability tofreely move and position gripping actuators in the form ofelectroadhesive gripping surfaces with respect to a handled foreignobject. Although only two fingers having three segments each are shownfor purposes of illustration, it will be understood that further fingersand/or more segments per finger can be used, as well as additional modesof freedom for each segment with respect to any neighboring segments. Inshort, any and all suitable robotic embodiments that enable theplacement of electroadhesive end effectors or gripping surfaces anywhereabout any surface of a foreign object to be handled are contemplated.Various specific examples of three segment two finger arrangements willnow be provided, although such examples are not intended to be limiting.

Continuing to FIG. 9A, one exemplary arrangement of the two fingers ofthe electroadhesive gripping system of FIG. 8 as applied to a foreignobject having a large flat surface is shown in side elevated view.Electroadhesive gripping system 900 includes numerous components, suchas those set forth in FIG. 8, although only the finger segments areshown here for purposes of simplicity. Each of finger segments orelectroadhesive gripping surfaces 910 a, 910 b, 910 c, 910 d, 910 e, 910f, as well as the various hinges or connectors 974 can be identical orsubstantially similar to the respective electroadhesive grippingsurfaces 810 x from foregoing gripping system 800. In this particularconfiguration, a plurality of electroadhesive gripping surfaces 910 a,910 b, 910 e, 910 f from both fingers have been placed up against flatforeign object 914. In some embodiments, gripping surfaces 910 c, 910 ddo not have enough freedom of movement with respect to any applicablebase robotic components to which they are coupled, while in otherembodiments (not shown), these gripping surfaces can also be placed upagainst foreign object 914. Once all appropriate electroadhesivegripping surfaces 910 x have been placed up against foreign object 914,then voltage can be applied and the foreign object can be lifted orotherwise handled thereby. Alternatively, voltage can be applied earlyand maintained while the various gripping surfaces remain in contactwith the foreign object.

Another configuration example is shown in FIG. 9B, which illustrates thesame electroadhesive gripping system as applied to a foreign objectcomprising a small pin. Electroadhesive gripping system configuration901 includes the same two fingers having three segments orelectroadhesive gripping surfaces each. In particular, electroadhesivegripping surfaces 910 c and 910 d are coupled to base robotic components(not shown), while electroadhesive gripping surfaces 910 a and 910 frepresent the last end effectors at the tips of both fingers. As shown,the fingers and gripping surfaces have been arranged such that pin 915can be suitably gripped. Such a gripping can be accomplished by usingone or more of the smaller side surfaces of one or more electroadhesivegripping surfaces, as shown.

Still another configuration example is shown in FIG. 9C, whichillustrates the same electroadhesive gripping system in top plan viewapplied to a foreign object comprising a medium sized ball.Electroadhesive gripping system configuration 902 again includes thesame two fingers having three segments or electroadhesive grippingsurfaces each, with electroadhesive gripping surfaces 910 a and 910 fagain representing the last end effectors at the tips of both fingers.As shown, the fingers and gripping surfaces have been arranged such thatball 916 can be suitably gripped. Such a gripping can be accomplished byusing just the fingertip electroadhesive gripping surfaces 910 a and 910f, as shown, again due to the relative small size of the object. It willbe understood that more or all of the electroadhesive gripping surfacescould be applied in the event that a larger foreign object is to behandled, or if the additional simplicity of a lower powered “all on orall off” system is desired.

Electroadhesive gripping system 902 also introduces multiple actuatingcomponents 980 that are configured to position the variouselectroadhesive gripping surfaces 910 x with respect to each other. Suchactuating components can include, for example, a cable driven by anactuator, an electromagnetic motor, a stepper motor, a hydraulic system,a pneumatic system, a shape memory alloy, and an electroactive polymer,among other possibilities. As shown in FIG. 9C, a thin layer across theback of adjacent electroadhesive gripping surfaces can be anelectroactive polymer that is adapted to flex and thereby move orposition the gripping surfaces when a suitable voltage is appliedthereto.

As can be seen in at least electroadhesive gripping system configuration902, the normal lines to the surface of foreign object 916 created bythe surfaces of contact between the electroadhesive gripping surfaces910 a, 910 f are clearly not substantially parallel with respect to eachother. In fact, the same contact surfaces made by the gripping actuatorcomponents (i.e., gripping surfaces) against ball 916 simply could notbe used by a traditional mechanically pinching gripping system. Thisflexibility in actuator or electroadhesive gripping surface placement isbeneficial not only in terms of convenience, but again also because ofthe weight and cost savings considerations noted above.

An alternative actuating component arrangement can include the use ofinterlocking meta-materials. Such meta-materials can similarly belocated across the backs or other suitable locations of eachelectroadhesive gripping surface, and can be used alone or inconjunction with one or more additional actuating components to helpposition the various gripping surfaces before the electroadhesionvoltages are applied thereto. In the case of the meta-materials, aninitial flexible uncharged state allows for the relatively free movementof adjacent components, while a subsequent charged or stiffened statesubstantially prevents or restricts relative movement of the sameadjacent components. Further details regarding such meta-materials andvarious applications thereof can be found at, for example, commonlyowned U.S. Pat. Nos. 7,598,691 and 7,598,692, which are incorporated byreference herein in their entirety and for all purposes.

In various embodiments, which can include any of the foregoing examplesor embodiments, the electrostatic adhesion voltage does not vary in timeand may be turned on or off. In various other embodiments, theelectrostatic adhesion voltage may be time-varying on each electrode,and may even reverse polarity at regular time-intervals to facilitaterapid attachment and detachment of the foreign object from any desiredelectroadhesive gripping surface(s) and/or end effector(s). In someembodiments, the electrostatic adhesion voltage might not be switchedoff sharply to release the foreign object, but rather polarity can bereversed for a fixed amount of time in order to ensure a rapid releaseof the object. In still further embodiments, the electrostatic adhesionvoltage can have polarity reversed with a decreasing magnitude over timein order to facilitate rapid release of the object.

In various embodiments, the applied electroadhesive voltage or grippingforce can be reduced or varied on one or more of the electroadhesivegripping surfaces to allow for greater flexibility in manipulating orcontrolling the foreign object. For instance, a reduction in voltage orforce at one or more select gripping surface(s) can result in theforeign object slipping or being repositioned within the electroadhesivegripping system. Such a variable electroadhesive force can be used tomodulate friction between a gripping surface and the object, so as toreposition objects by controllably sliding objects within or about thegripping surface. A suitable increased electroadhesive gripping forcecan then be reapplied after such a controlled slip or repositioning. Asa specific non-limiting example, one or all of the electroadhesivegripping surfaces on segments 910 a and 910 f in FIG. 9C can have thevoltage provided thereto reduced such that the gripped foreign object916 slips a certain amount. After a desired amount of slippage, asufficient voltage can be reapplied to strengthen the electroadhesivegrip again. Such controlled variances in voltage and resultingelectroadhesive force can be particularly effective when multiplefingers or end effectors with numerous electroadhesive gripping surfacesare used, such as in the case of the robotic hand embodiment of FIG. 10below.

Still further applications can involve even more complex and integratedsystems involving more fingers and more electroadhesive grippingsurfaces. Moving next to FIG. 10 an exemplary robotic hand havingnumerous fingers, electroadhesive gripping surfaces and actuators isshown in front perspective view. Electroadhesive gripping robotic hand1000 can include numerous hand-like components, such as a palm region,three fingers 1071 a, 1070 b, 1070 c and an opposable thumb 1075. Eachof these items can include multiple electroadhesive gripping surfaces1010 x, which are preferably movable and configurable with respect toeach other. For example, electroadhesive gripping surfaces 1010 a, 1010b and 1010 c are located on the fingers of robotic hand 1000,electroadhesive gripping surfaces 1010 d and 1010 e are located on thepalm region of the hand, and electroadhesive gripping surfaces 1010 fand 1010 g are located on the opposable thumb 1075. Furtherelectroadhesive gripping surfaces are also present on the hand 1000, andeven more can be included if desired, although a complete listing is notprovided here for purposes of simplicity.

The three fingers 1070 a, 1070 b, 1070 c and palm region 1010 d, 1010 ecan be controlled in part through the use of multiple cables 1081, whichcan be driven by actuators. These cables driven by actuators, or anyother suitable actuating components for that matter, do not necessarilyneed to be able to carry heavy loads, as their primary purpose is toposition the various electroadhesive gripping surfaces about thesurfaces of a handled foreign object. In various embodiments, the cableactuators 1081 can be used to independently control each finger 1070 xseparately, such that the fingers can extend in different directions andlengths, as may be desired. Various further details regarding cableactuators in robotic applications will be readily understood by thoseskilled in the art, and are not of special focus here.

In addition to the various fingers, electroadhesive gripping surfacesand actuating components, a plurality of sensors 1090 or other feedbackcomponents can also be included on electroadhesive gripping robotic hand1000. Such sensors 1090 or feedback items can be used to detect when aforeign object is suitably gripped, when a gripped object is slipping ormoving, and/or how much of a foreign object is gripped (e.g., number ofsheets of paper), among other potentially detected items, such ascontact or slip. This information can be used to manually orautomatically correct or adjust voltage, positioning, motion and/orother aspects of the hand, fingers or thumb, as may be appropriate. Inapplications where such sensing elements are located directly behind theelectroadhesive gripping surfaces and can be affected by theelectroadhesive gripping voltages, a separate conductive shielding layercan be incorporate to minimize these interactions. This shielding layercan be located either on the outer surface of the sensor layer orintegrated into the appropriate surface (such as on the surface oppositeto the one that is in contact with the foreign object to be gripped ormanipulated).

Still further applications can involve the use of electroadhesivegripping surfaces to assist users with gripping tough object, or in theevent of user arthritis or hand tremors, for example. FIG. 11Aillustrates in side perspective view an exemplary application of awearable glove having multiple electroadhesive gripping surfaces locatedalong its outer surfaces according to one embodiment of the presentinvention. Wearable glove 1100 includes a number of electroadhesivegripping surfaces, such as gripping surfaces 1110 a, 1110 b, and 1110 con the index finger, gripping surfaces 1110 d and 1110 e located acrossa palm region, and gripping surfaces 1110 e and 1110 f located on thethumb. A suitably strong insulator can be used between theelectroadhesive gripping surfaces and the inner region where the hand ofa user is inserted, so as to provide safety to the user. A suitableapplication of voltage across various electroadhesive gripping surfaces1110 x can then aid the wearer in gripping an object.

An exemplary application of such a wearable glove is to reduce themechanical force that needs to be exerted by the person's fingers tosecurely grip an object. Another exemplary application is shown in FIG.11B, which illustrates in block diagram format the wearable glove ofFIG. 11A being used to aid in the gripping of a bag strap to carry anassociated bag. As shown in exemplary arrangement 1150, the hand of auser is inserted into wearable glove 1100, after which the fingers ofthe hand and glove combination are placed underneath a strap or handlefor attached foreign object 1114. Weighted bag 115 can then be strappedto or otherwise supported by foreign object 1114. Once the fingers ofthe hand and glove combination are placed through the appropriate strapor handle, a button or other actuator can be pressed to activate thevoltage to the various electroadhesive gripping surfaces on the surfaceof the glove 1100. This can effectively render the glove as stiff, suchthat no further gripping force is needed by the user upon actuallylifting the object 1114 and bag 1115.

Method of Use

Although an immense variety of applications and methods of lifting,moving or otherwise handling an object using the electroadhesive endeffectors, gripping surfaces and other arrangements as described hereincan be imagined, a basic method of moving an object is provided here asan example. Turning lastly to FIG. 12, a flowchart of an exemplarymethod of moving an object using electroadhesive force according to oneembodiment of the present invention is provided. It will be readilyappreciated that not every method step set forth in this flowchart isalways necessary, and that further steps not set forth herein may alsobe included. Furthermore, the exact order of steps may be altered asdesired for various applications.

Beginning with a start step 1200, a first electroadhesive grippingsurface is placed against a first surface region of a foreign object atprocess step 1202. Again, such a placement results in a first linenormal to a first surface of contact between the first electroadhesivegripping surface and the foreign object surface. At subsequent processstep 1204, a second electroadhesive gripping surface is moved withrespect to the first electroadhesive gripping surface. Such movementcould also take place prior to the first gripping surface being placedagainst the foreign object, if desired. At the following process step1206, the second electroadhesive gripping surface is then placed againstthe foreign object. Again, such a placement results in a second linenormal to a second surface of contact between the second electroadhesivegripping surface and the foreign object surface. In one embodiment,these first and second normal lines are not substantially parallel withrespect to each other. This can be considered as the first and secondsurfaces of contact not lying within the same plane. It will be readilyappreciated that some embodiments may arise where the normal lines areparallel, but the first and second surfaces still do not lie within thesame plane, and such embodiments are contemplated for use in the presentinvention.

After process step 1206, a decision step 1208 inquires as to whether allelectroadhesive gripping surfaces have been placed against the foreignobject. If not, then an additional electroadhesive gripping surface isplaced against the foreign object at process step 1210, after whichdecision step 1208 is repeated. If all electroadhesive gripping surfacesthat are to be used have been placed, however, then the method continuesto process step 1212, where a first electrostatic adhesion voltage isapplied to the first electroadhesive gripping surface. At process step1214, further electrostatic adhesion voltage(s) are applied to thesecond and any other additional electroadhesive gripping surfaces. Inone embodiment, such voltages can be applied in order at differenttimes, and in another embodiment, such voltages can be appliedsimultaneously (i.e., steps 1212 and 1214 are performed in parallel). Instill further embodiments, such voltages can be applied prior to thegripping surfaces being placed up against the foreign object.

Once all of the appropriate voltages are applied, such that the foreignobject is suitably clamped or coupled to the electroadhesive grippingsurfaces and is thereby “gripped,” then the gripping surfaces grippingthe foreign object are moved while the voltages are on at process step1216. Of course, such movement of the activated electroadhesive grippingsurfaces results in the movement or handling of the foreign object aswell. The method then finishes at and end step 1218. Further steps notdepicted can include, for example, reducing or turning off theelectroadhesive voltage to the electroadhesive gripping surfaces, andremoving the electroadhesive end effectors or gripping surfaces from theforeign object. Still further steps can include reducing or varying theapplied electroadhesive voltage or gripping force, such that the foreignobject can be allowed to slip or be repositioned within theelectroadhesive gripping system. A suitable increased electroadhesivegripping force can then be reapplied after such a controlled slip orrepositioning, as desired.

Although the foregoing invention has been described in detail by way ofillustration and example for purposes of clarity and understanding, itwill be recognized that the above described invention may be embodied innumerous other specific variations and embodiments without departingfrom the spirit or essential characteristics of the invention. Variouschanges and modifications may be practiced, and it is understood thatthe invention is not to be limited by the foregoing details, but ratheris to be defined by the scope of the claims.

1. An electroadhesive gripping system, comprising: a firstelectroadhesive end effector having a first electroadhesive grippingsurface configured to be placed against a first surface region of aforeign object, said first electroadhesive gripping surface including atleast one electrode; and a second electroadhesive end effector having asecond electroadhesive gripping surface configured to be placed againsta second surface region of the foreign object, said secondelectroadhesive gripping surface including at least one electrode,wherein said first and second electroadhesive end effectors are adaptedto move independently with respect to each other, and wherein said firstand second electroadhesive gripping surfaces combine to provide anoverall electroadhesive force that operates to hold the foreign objectagainst said first and second electroadhesive gripping surfaces whilethe foreign object is controlled by the electroadhesive gripping system.2. The electroadhesive gripping system of claim 1, wherein said firstelectroadhesive gripping surface includes a first electrode configuredto apply a first voltage at a first surface location at said firstsurface region and a second electrode configured to apply a secondvoltage at a second surface location at said first surface region of theforeign object, wherein the difference in voltage between the firstvoltage and second voltage includes a first electrostatic adhesionvoltage that produces a local electroadhesive force.
 3. Theelectroadhesive gripping system of claim 2, wherein said firstelectroadhesive gripping surface is less than about 1 millimeter fromthe surface of the foreign object when said first electrostatic adhesionvoltage is on.
 4. The electroadhesive gripping system of claim 2,further including: an insulation material disposed between said firstelectrode and said second electrode and configured to substantiallymaintain said first electrostatic adhesion voltage difference betweensaid first and second electrodes.
 5. The electroadhesive gripping systemof claim 1, further including: an actuating component coupled to saidfirst electroadhesive gripping surface, said actuating componentconfigured to help position said first electroadhesive gripping surfacewith respect to the foreign object.
 6. The electroadhesive grippingsystem of claim 5, wherein said actuating component is selected from thegroup consisting of a cable driven by an actuator, an electromagneticmotor, a stepper motor, a hydraulic system, a pneumatic system, a shapememory alloy, and an electro active polymer.
 7. The electroadhesivegripping system of claim 1, wherein said overall electroadhesive forceis a variable force that depends upon a variable voltage delivered tothe electrodes of said first and second electroadhesive end effectors.8. The electroadhesive gripping system of claim 7, wherein said overallelectroadhesive force can be varied such that only a portion of saidforeign object is controlled by the electroadhesive gripping system. 9.The electroadhesive gripping system of claim 1, further including: athird electroadhesive gripping surface configured to be placed against athird surface region of the foreign object, said third electroadhesivegripping surface including at least one electrode.
 10. Theelectroadhesive gripping system of claim 1, wherein said first andsecond electroadhesive gripping surfaces operate to pick, lift,manipulate and place the foreign object.
 11. The electroadhesivegripping system of claim 1, wherein said first electroadhesive grippingsurface further includes a deformable surface portion adapted to conformto at least one aspect particular to the first surface region of theforeign object.
 12. The electroadhesive gripping system of claim 11,wherein said deformable surface portion is adapted to move closer to thefirst surface region of the foreign object when voltage is applied tosaid first electroadhesive gripping surface.
 13. The electroadhesivegripping system of claim 1, wherein the foreign object has a round,cylindrical or irregular three-dimensional shape.
 14. Theelectroadhesive gripping system of claim 13, wherein the first surfaceregion of the foreign object defines a three-dimensional profile, andwherein said first electroadhesive gripping surface comprises a fixedthree-dimensional shape that conforms to the three-dimensional profileof the first surface region.
 15. The electroadhesive gripping system ofclaim 13, wherein the first surface region of the foreign object definesa three-dimensional profile, and wherein said first electroadhesivegripping surface comprises a flexible material adapted to conform to thethree-dimensional profile of the first surface region.
 16. Anelectroadhesive gripper, comprising: a first electroadhesive grippingsurface configured to be placed against a first surface region of aforeign object, said first electroadhesive gripping surface including atleast one electrode; and a second electroadhesive gripping surfaceconfigured to be placed against a second surface region of the foreignobject, said second electroadhesive gripping surface including at leastone electrode, wherein said first and second electroadhesive grippingsurfaces are separate and distinct with respect to each other, andwherein said first and second electroadhesive gripping surfaces combineto provide an overall electroadhesive force that operates to hold theforeign object against said first and second electroadhesive grippingsurfaces while the foreign object is held, moved or manipulated by theelectroadhesive gripper.
 17. The electroadhesive gripper of claim 16,further including: a first cable driven by an actuator coupled to bothof said first and second electroadhesive gripping surfaces, wherein saidfirst cable driven by an actuator operates to position both of saidfirst and second electroadhesive gripping surfaces with respect to theforeign object prior to the electroadhesive gripper gripping the foreignobject, and wherein said overall electroadhesive force operates to holdthe foreign object against said first and second electroadhesivegripping surfaces while the foreign object is held, moved or manipulatedby the electroadhesive gripper.
 18. The electroadhesive gripper of claim16, wherein said first and second electroadhesive gripping surfaces areadapted to move independently with respect to each other.
 19. Theelectroadhesive gripper of claim 16, wherein said first and secondelectroadhesive gripping surfaces are formed along a first continuousfinger of said electroadhesive gripper, the electroadhesive gripperfurther comprising: a second continuous finger having a plurality ofadditional separate and distinct electroadhesive gripping surfaces, eachof said plurality of additional separate and distinct electroadhesivegripping surfaces having at least one electrode.
 20. The electroadhesivegripper of claim 19, wherein each of said first continuous finger andsaid second continuous finger are adapted to extend aroundthree-dimensional surface regions of the foreign object in differentdirections.
 21. The electroadhesive gripper of claim 16, wherein atleast one feature of said first electroadhesive gripping surfacecomprises a deformable surface portion adapted to conform to the firstsurface region of the foreign object.
 22. The electroadhesive gripper ofclaim 21, wherein said deformable surface portion is adapted to movecloser to the first surface region of the foreign object when voltage isapplied to said first electroadhesive gripping surface.
 23. A method ofgripping an object, comprising: placing a first electroadhesive grippingsurface having at least one electrode against a first surface region ofa foreign object; placing a second electroadhesive gripping surfacehaving at least one electrode against a second surface region of theforeign object, the second surface region being spaced apart from thefirst surface region; and applying or maintaining a first electrostaticadhesion voltage difference at a plurality of the electrodes on saidfirst and second electroadhesive gripping surfaces such that a firstelectrostatic attraction force is created between one or both of saidfirst and second electroadhesive gripping surfaces and the foreignobject.
 24. The method of claim 23, further including the step of:moving said second electroadhesive gripping surface independently withrespect to said first electroadhesive gripping surface.
 25. The methodof claim 24, wherein said step of moving said second electroadhesivegripping surface with respect to said first electroadhesive grippingsurface includes using an actuator selected from the group consisting ofa cable driven by an actuator, an electromagnetic motor, a steppermotor, a hydraulic system, a pneumatic system, a shape memory alloy, andan electroactive polymer.
 26. The method of claim 23, wherein each ofsaid first and second electroadhesive gripping surfaces includes aplurality of electrodes, and wherein each of said first and secondelectroadhesive gripping surfaces are adapted to provide a localizedelectrostatic adhesion voltage difference at their respect surfaceregions of the foreign object.
 27. The method of claim 23, furtherincluding the step of: applying a second electrostatic adhesion voltagedifference at a different plurality of the electrodes of one or both ofsaid first and second electroadhesive gripping surfaces such that asecond electrostatic attraction force is created between one or both ofsaid first and second electroadhesive gripping surfaces and the object.28. An electroadhesive gripping system, comprising: a firstelectroadhesive gripping surface configured to be placed against a firstsurface region of a three-dimensional foreign object, said firstelectroadhesive gripping surface including at least one electrode and adeformable surface portion adapted to conform to at least one aspectparticular to the first surface region; and a second electroadhesivegripping surface configured to be placed against a second surface regionof the foreign object, said second electroadhesive gripping surfaceincluding at least one electrode, wherein said first and secondelectroadhesive gripping surfaces combine to provide an overallelectroadhesive force that operates to hold the foreign object againstsaid first and second electroadhesive gripping surfaces while theforeign object is held or moved by the electroadhesive gripping system.29. The electroadhesive gripping system of claim 28, wherein saiddeformable surface portion is adapted to move closer to the firstsurface region of the foreign object when voltage is applied to saidfirst electroadhesive gripping surface.
 30. The electroadhesive grippingsystem of claim 28, wherein said first and second electroadhesivegripping surfaces are adapted to be moved independently with respect toeach other.
 31. The electroadhesive gripping system of claim 28, whereinsaid first and second electroadhesive gripping surfaces are part of thesame electroadhesive end effector.
 32. The electroadhesive grippingsystem of claim 31, wherein said electroadhesive end effector resemblesa human hand.
 33. The electroadhesive gripping system of claim 31,wherein said electroadhesive end effector defines a thin and flexibleveil having a plurality of electrode pairs, each electrode pair defininga separate gripping surface.